The Caucasus is a diverse region with many climate zones that range from subtropical lowlands to mountainous alpine areas. The region is marked by irrigated croplands fed by irrigation canals, ...heavily vegetated wetlands, lakes, and reservoirs. In this study, we demonstrate the development of an improved surface water map based on a global water dataset to get a better understanding of the spatial distribution of small water bodies. First, we used the global water product from the European Commission Joint Research Center (JRC) to generate training data points by stratified random sampling. Next, we applied the optimal probability cut-off logistic regression model to develop surface water datasets for the entire Caucasus region, covering 19 Landsat tiles from May to October 2019. Finally, we used 6745 manually classified points (3261 non-water, 3484 water) to validate both the newly developed water dataset and the JRC global surface water dataset using an estimated proportion of area error matrix to evaluate accuracy. Our approach produced surface water extent maps with higher accuracy (89.2%) and detected 392 km2 more water than the global product (86.7% accuracy). We demonstrate that the newly developed method enables surface water detection of small ponds and lakes, flooded agricultural fields, and narrow irrigation channels, which are particularly important for mosquito-borne diseases.
The urban heat island (UHI) effect is a global problem that is likely to grow as a result of urban population expansion. Multiple studies conclude that green spaces and waterbodies can reduce urban ...heat islands. However, previous studies often treat urban green spaces (UGSs) as static or limit the number of green spaces investigated within a city. Cognizant of these shortcomings, Landsat derived vegetation and land surface temperature (LST) metrics for 80 urban green spaces in Puebla, Mexico, over a 34-year (1986–2019) and a 20-year (2000–2019) period were studied. To create a photo library, 73 of these green spaces were visited and the available land cover types were recorded. Green spaces with Indian laurel were found to be much greener and vegetation index values remained relatively stable compared to green spaces with mixed vegetation cover. Similarly, green spaces with large waterbodies were cooler than those without water. These results show that larger green spaces were significantly cooler (p < 0.01) and that size can explain almost 30% of temperature variability. Furthermore, green spaces with higher vegetation index values were significantly cooler (p < 0.01), and the relationship between greenness and temperature strengthened over time.
We report a 6-year study of an irruptive invasion of emerald ash borer (EAB) into a 36-year-old comparison of 60 green ash (
Fraxinus pennsylvanica
Marsh.) and 5 white ash (
F. americana
L.) ...populations. As the infestation progressed, annual measures of EAB injury (density of adult emergence holes on the trunk, crown condition, and mortality) were significantly influenced by genetic effects (population and in some instances family within population), site quality (field blocks), and neighborhood (contagion effects over distances of 5–13 m). At the last measurement, 99% of green ash trees and 87% of white ash were dead, and most of the remaining few trees had badly deteriorating crowns. Although final destruction was nearly complete, the rapidity with which trees were injured and killed was moderated by genetic and site effects and influenced by proximity to infested trees. These facts suggest that some genotypes, especially on favorable sites, will disproportionately survive under future equilibrium conditions with lower densities of ash and EAB in the landscape.
The Rio Grande/Bravo is an arid river basin shared by the United States and Mexico, the fifth-longest river in North America, and home to more than 10.4 million people. By crossing landscapes and ...political boundaries, the Rio Grande/Bravo brings together cultures, societies, ecosystems, and economies, thereby forming a complex social-ecological system. The Rio Grande/Bravo supplies water for the human activities that take place within its territory. While there have been efforts to implement environmental flows (flows necessary to sustain riparian and aquatic ecosystems and human activities), a systematic and whole-basin analysis of these efforts that conceptualizes the Rio Grande/Bravo as a single, complex social-ecological system is missing. Our objective is to address this research and policy gap and shed light on challenges, opportunities, and success stories for implementing environmental flows in the Rio Grande/Bravo. We introduce the physical characteristics of the basin and summarize the environmental flows studies already done. We also describe its water governance framework and argue it is a distributed and nested governance system across multiple political jurisdictions and spatial scales. We describe the environmental flows legal framework and argue that the authority over different aspects of environmental flows is divided across different agencies and institutions. We discuss the prioritization of agricultural use within the governance structure without significant provisions for environmental flows. We introduce success stories for implementing environmental flows that include leasing of water rights or voluntary releases for environmental flow purposes, municipal ordinances to secure water for environmental flows, nongovernmental organizations representing the environment in decision-making processes, and acquiring water rights for environmental flows, among others initiatives. We conclude that environmental flows are possible and have been implemented but their implementation has not been systematic and permanent. There is an emerging whole-basin thinking among scientists, managers, and citizens that is helping find common-ground solutions to implementing environmental flows in the Rio Grande/Bravo basin.
Forest trees are beleaguered by the ever-increasing onslaught of invasive pests and pathogens, with some species in danger of functional extinction. Recent successes in developing resistant ...populations using traditional tree breeding assures that some of the affected species will persist in future forests. However, the sheer number of threatened species requires increases in breeding efficiency. The time is right to consider how the use of genomic resources might aid breeding efforts in the next 20 years. Any operational benefit of genomic resources will be minimal without closer collaboration between tree breeders, forest managers, and genomic researchers. We reflect here on what attributes were responsible for the success of traditional resistance breeding programs and whether advances in genomics can realistically accelerate breeding. We conclude that the use of genomics to directly advance resistance breeding efforts in the next 20 years will be limited. Major obstacles will include factors such as the undomesticated nature of most tree species, the quantitative genetic nature of resistance in many species, and the lack of adequate funding to accelerate and more fully develop genomic resources. Despite these limitations, genomic tools have potential to help increase our understanding of the nature of resistance, and the genetic variability in the host, which can aid in the deployment of resistant populations and may assist in marker-assisted selection, particularly for major gene resistance.
Ashes (
Fraxinus spp.
) are important hardwood tree species in rural, suburban, and urban forests of the eastern USA. Unfortunately, emerald ash borer (EAB,
Agrilus planipennis
) an invasive insect ...pest that was accidentally imported from Asia in the late 1980s–early 1990s is destroying them at an alarming rate. All North American ashes are highly susceptible to EAB, although blue ash (
F. quadrangulata
) may have some inherent attributes that provide it some protection. In contrast Manchurian ash (
F. mandshurica
) is relatively resistant to EAB having coevolved with the insect pest in its native range in Asia. Given its level of resistance, Manchurian ash has been considered for use in interspecies breeding programs designed to transfer resistance to susceptible North American ash species. One prerequisite for successful interspecies breeding is consistency in chromosome ploidy level and number between the candidate species. In the current study, we cytologically determined that both Manchurian ash and blue ash are diploids (2
n
) and have the same number of chromosomes (2
n
= 2
x
= 46). We also characterized these species’ ribosomal gene families (45S and 5S rDNA) using fluorescence in situ hybridization (FISH). Both Manchurian and blue ash showed two 45S rDNA and one 5S rDNA sites, but blue ash appears to have an additional site of 45S rDNA. The 5S rDNA in both species is colocalized interstitially with one of the 45S rDNA sites. The copy number of these two ribosomal gene families in Manchurian ash were observed to be quite varied, which indicates the species are still undergoing evolutionary homogenization.
Introduction
Larvae of the invasive emerald ash borer EAB,
Agrilus planipennis
Fairmaire (Coleoptera: Buprestidae), kill over 99% of green ash (
Fraxinus pennsylvanica
Marshall) trees they infest, ...yet a small percentage of green ash (“lingering ash”) survive years of heavy EAB attack. In the face of an ongoing invasion that threatens multiple North American
Fraxinus
species with extinction, any evidence for reproducible defensive responses in the native species merits investigation.
Methods
We evaluated the capacity of three families of green ash F
1
progeny to kill EAB larvae when challenged in greenhouse studies by infestation with a uniform density of EAB eggs followed by dissection 8 weeks post-infestation and comparison of the host metabolomic profiles.
Results
The mean proportions of host-killed larvae in the two families of F
1
progeny from lingering ash parents were significantly higher than that of host-killed larvae in the family of F
1
progeny from susceptible ash parents (
p
< 0.001). Untargeted metabolomics comparing F
1
progeny in the quartile with the highest percent host-killed larvae (HHK) to F
1
progeny in the quartile with the lowest percent host-killed larvae (LHK) and to the uninfested F
1
progeny within each family revealed evidence for induced biochemical responses to EAB. Infested trees produced significantly higher levels of select secoiridoids than uninfested trees, and LHK progeny produced significantly higher levels of select secoiridoids than the HHK progeny. HHK progeny produced significantly higher abundances of three metabolites annotated as aromatic alkaloids than the LHK and uninfested individuals.
Discussion
Based on these results, we hypothesize that green ash responds to EAB infestation. However, only certain trees have the genetic capacity to tailor a response that kills enough EAB larvae to prevent lethal damage to the vascular system. Rigorous tests of this hypothesis will require 15–20 years of additional crossing, phenotyping, and omics analyses. The results of this investigation will encourage the establishment and continuation of breeding programs that, in concert with biocontrol and management, could provide trees that slow, if not halt, the decimation of the
Fraxinus
gene pool. At the same time, ongoing work on host-insect interaction will contribute to our understanding of how forest trees recognize and defend themselves against phloem-feeding insects.
Emerald ash borer (
Agrilus planipennis
; EAB) has devastated populations of ash (
Fraxinus
spp.) trees in dozens of U.S. states and Canada over the past few decades. The continued survival of ...scattered ash trees known as “lingering ash” in heavily infested natural stands, however, offers evidence of genetic resistance or tolerance to EAB. These surviving or “lingering” ash individuals may form the basis for reforestation programs in EAB-impacted areas, and clonal mass-propagation of these genotypes can help accelerate these efforts. Between 2013 and 2018, we initiated embryogenic cultures by culturing immature zygotic embryos from open-pollinated (OP) seeds collected from several surviving white ash and green ash trees in Michigan and Pennsylvania. In addition, in 2018, we initiated cultures from crosses made between lingering green ash parents from the USDA Forest Service ash breeding program in Ohio. Somatic embryos were produced by growing cultures in liquid suspension, followed by fractionation and plating on semisolid medium to produce developmentally synchronous populations of somatic embryos. Somatic embryo germination and conversion were enhanced by a combination of pre-germination cold treatment and inclusion of activated charcoal and gibberellic acid in the germination medium. Ash somatic seedlings derived from OP explants grew rapidly following transfer to potting mix and somatic seedlings representing nine ash clones were acclimatized, grown in the greenhouse and planted in a preliminary field test, along with EAB-resistant Manchurian ash (
F. mandshurica
) and EAB-susceptible control seedlings. Somatic seedlings have now been produced from cultures that originated from seeds derived from the progeny of lingering green ash parents and an ex vitro germination protocol has shown some promise for accelerating early somatic seedling growth. Results of this research could provide the basis for scaled-up production of EAB-resistant ash varieties for seed orchard production for forest restoration and cultivar development for urban tree restoration.
The American Beech tree (Fagus grandifolia Ehrh.), native to eastern North America, is ecologically important and provides high quality wood products. This species is susceptible to beech bark ...disease (BBD) and is facing high rates of mortality in North America. The disease occurs from an interaction between the woolly beech scale insect (Cryptococcus fagisuga), one of two species of the fungus Neonectria (N. faginata or N. ditissima), and American Beech trees.
In this case-control genome-wide association study (GWAS), we tested 16 K high quality SNPs using the Affymetrix Axiom 1.5 K - 50 K assay to genotype an association population of 514 individuals. We also conducted linkage analysis in a full-sib family of 115 individuals. Fisher's exact test and logistic regression tests were performed to test associations between SNPs and phenotypes.
Association tests revealed four highly significant SNPs on chromosome (Chr) 5 for a single gene (Mt), which encodes a mRNA for metallothionein-like protein (metal ion binding) in Fagus sylvatica. Metallothioneins represent Cys-rich metal chelators able to coordinate metal atoms and may play an important role in the resistance mechanisms against beech scale insect.
The GWAS study has identified a single locus of major effect contributing to beech bark disease resistance. Knowledge of this genetic locus contributing to resistance might be used in applied breeding, conservation and restoration programs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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